- Feuille de thé vert
- Sachets de thé vert
- Thé vert en poudre Matcha
- Thé vert organique
- Tsuen Tea
- Articles de thé
- Idées cadeaux de thé vert
- Thé vert japonais à édition limitée
Green Tea Health Benefits
What's with all the hype about green tea health benefits?
Ordinary tea, as most people know it, comes from the leaves of the camellia sinensis plant. There are three main types of tea: green tea, oolong tea, and black tea, categorized according to their oxidation levels (called the fermentation process). Green tea is steamed, baked, or pan heated to prevent oxidation and thus the leaves remain green. Unlike green tea, oolong tea is partially fermented, and black tea is fully fermented.
So why is green tea getting all the attention in the science world? It's mainly because of the antioxidant epigallocatechin-3 gallate ( EGCG ), the main component considered good for one's health which is preserved in green tea but lost in oolong and black varieties when fermented. Antioxidants are thought to prevent free radicals.
Free Radicals - What exactly is a free radical?
A scientific explanation: In essence, a free radical is any molecular species capable of independent existence, that contains one or more unpaired electrons not contributing to intermolecular bonding, and is, in that sense, "free". They are produced by oxidation/reduction reactions, in which there is a transfer of only one electron at a time, or when a covalent bond is broken and one electron from each pair remains with each atom. Thus, a free radical has an unpaired electron.
Many free radicals are highly reactive, owing to the tendency of electrons to pair; that is, to pair by the receipt of an electron from an appropriate donor or to donate an electron to an appropriate acceptor. Whenever a free radical reacts with a non-radical, a chain reaction is initiated until two free radicals react and then terminate the propagation with a 2-electron bond, with each radical contributing its single unpaired electron. The free radicals of special interest in aging are the oxygen free radicals (OH., H., O2.-). These free radicals often take an electron away from a "target" molecule to pair with their single free electron; this is what is commonly termed oxidation. The term reactive oxygen species is used to refer to these oxidants and the oxygen free radicals.
In the human body, oxidized free radicals are believed to cause tissue damage at the cellular level, causing damage to our DNA, mitochondria (the powerhouse of the cell), and cell membrane, and have often been referred to as one of the causes attributed to aging, cancer, heart disease, and other human ailments harmful to one's health. While the green tea ion of free radicals is a normal part of metabolism at the cellular level, things such as excessive alcohol intake, smoking, and various chemical exposures only serve to increase the amount of free radicals present in the body. To prevent free radical damage the body has a defense system of antioxidants.
Antioxidants - What exactly is an antioxidant?
Antioxidants are molecules which can safely interact with free radicals and terminate the chain reaction before vital molecules are damaged (as in Vitamin C), or seek out and scavenge free radicals ( as in Vitamin E ). This is where it can be noted that research has indicated that one of the main antioxidants found in green tea ( epigallocatechin 3-gallate a.k.a. EGCG ) has been found to be much more powerful than both Vitamins C and E. Compared to other known antioxidants, EGCG was found to be 100 times more effective than vitamin C, 25 times more effective than Vitamin E and twice as powerful as resveratrol at neutralizing free radicals.
Green tea contains antioxidants properties, polyphenols, theanine, as well as a wide variety of vitamins and minerals. To understand green tea benefits for one's health, all you have to do is take a closer look at the compounds...
Properties in Green Tea
Polyphenols are a class of phytochemical found in high concentrations in green tea, and have been associated with heart disease and cancer prevention. The slight astringent, bitter taste of green tea is attributed to polyphenols.
A group of simple and complex phenol, polyphenols, and flavonoid compounds. Produced by plants, all of the tannins are relatively resistant to digestion or fermentation.
Catechins are a category of polyphenols. In green tea, catechins are present in significant quantities, more specifically; epicatechin (EC), epigallocatechin (EGC), epicatechin gallate (ECG) and epigallocatechin gallate (EGCG). EGCG makes up about 10-50% of the total catechin content and appears to be the most powerful of the catechins, with antioxidant activity about 25-100 times more potent than vitamins C and E. A cup of green tea may provide 10-40mg of polyphenols and has antioxidant activity greater than a serving of broccoli, spinach, carrots or strawberries.
Flavonoids are plant pigments, and are the brightly colored chemical constituents found in most fresh fruits and vegetables. They may aid in protecting against infection.
An amino acid that produces tranquilizing effects in the brain, theanine is a unique amino acid found in the leaves sencha. Theanine is quite different from the polyphenols and catechin antioxidants for which green tea is typically consumed. Three to four cups of sencha are expected to contain 100-200 mg of theanine.
In the following chart, we compare the antioxidant properties of several different types of green teas
|Free Amino Acids